In an image pickup apparatus, such as a digital camera, which takes an image through conversion of an image signal to an electric signal, a beam of light from an object to be photographed is received by an image pickup element, such as a Charge Coupled Device (CCD) sensor or a Complementary Metal Oxide Semiconductor (CMOS) sensor. The signal after the photoelectric conversion, output from the image pickup element, is converted to image data and is recorded on a recording medium, such as a memory card. In the above-mentioned image pickup apparatus, a cover glass, an optical low-pass filter, an infrared absorption filter, etc. are arranged on the front side (i.e., the side nearer to the object) of the image pickup element.
In that type of image pickup apparatus, if foreign matter, such as dust, adheres to the surface of the cover glass or the filter of the image pickup element, incident light may be intercepted by the foreign matter, and the foreign matter may be captured as a black point in a photographed image. In a single-lens reflex camera, particularly, there is a possibility that dust may generate when mechanically operating members, such as a shutter and a quick return mirror, arranged near an image pickup unit are operated, and that dust may enter the camera through a lens mount opening when a lens is exchanged. Those dusts may adhere to the surface of the cover glass or the filter of the image pickup element. In view of the above situation, an image pickup apparatus and an image reading apparatus, each provided with a dust removing device to remove dust adhering to the surface of an optical component, are proposed in which a piezoelectric element is disposed on a cover glass or a filter of an image pickup element, and the cover glass or the filter of the image pickup element is bent to displace in the direction of thickness thereof by utilizing vibration of the piezoelectric element, thus causing the dust to be detached from the surface and to be flipped away with out-of-plane vibration (called “flexural vibration” hereinafter) (see Patent Literatures (PTLs) 1 and 2).
PTLs 1 and 2 each discloses a device in which a piezoelectric element is arranged outside an optical effective region of a rectangular optical filter (e.g., a low-pass filter or an infrared absorption filter) along an edge of the optical effective region, and dust adhering to the surface of the optical effective region is removed with vibration of the piezoelectric element.